I have a 2000 Jeep Cherokee Sport 4x4 with the inline 6 4.0 engine. It is automatic with Air Conditioning.

The problem I am having is that when the passing gear is kicked in by flooring the gas. The engine just revs at a steady 3050-RPM but the vehicle does not accelerate. If I take my foot off the gas the engine returns to normal operation, then if I slowly press on the gas pedal the vehicle will accelerate normally.

I swapped out the MAS, didn't fix it.

I swapped out the TPS, didn't fix it.

I tested flow on the exhaust, and it's breathing out fine.

I tested fuel pressure, it's fine.

I tested for vacuum leaks, it's fine.

The engine runs smooth as heck, it shifts through all gears smoothly and idles rock solid. No issues anywhere. But when I try to engage the passing gear it just sits there revving at 3050rpm and won't accelerate it just maintains the speed it is at when I floor it. This doesn't seem like a tranny issue as it would rev out if it were slipping. But I checked the tranny fluid anyway and it's full and clean.

Also, I just noticed that my ODBII port isn't communicating either. It has power and all the fuses are good, it just won't communicate.


Anybody experience this?? Any ideas?

 

 

I know this sounds really basic but have you tried disconnecting the battery and resetting the computer?

 

Also have your battery checked.. I just read a thread on naxja about a guy whose obd ii wasn't reading, he went through all kinds of work trying to figure it out and in the end he just needed a new battery.. you never know..

 

I haven't checked the battery. But that is a good idea to see if I can get the ODBII port communicating. Going to give that a try, thanks for the advice there.

 

torque converter toasted?

 

have you tried your tranny kickdown cable??

look for the threads on how to adjust the cable. It may be something as simple as that...

 

Hmmm...I am not noticing any shuddering or noises. Also, off the line the truck pulls normally. It is just when the passing gear kicks in that I am experiencing this problem. It's almost like it's starving for gas or choking or something as the revs are limited to 3050 RPM. But, I will look into a possible TC problem. Thanks for the reply.

 

Good call...Gonna check that out when I see if resetting the computer fixes my ODBII problem.

 

Ok...I disconnected the battery, and it cleared the code that was present, but my reader still won't communicate.

I also did that throttle cable adjustment that 96_xj recommended. I did notice a noticeable change in my shift points, which was nice. ...But the problem with the truck not accelerating when kicked down into the passing gear is still the same.

 

hmmm does it do the same if you go into "3" and try to pass? is it an only in "D" problem?

 

also you need to disconnect the positive and touch it to your negative terminal for 30 seconds. that will reset the computer as it draws out the memory in the system. But now you have to remember it puts it into "learning mode" for the next 50 starts (or factory break in period).


also have you looks to see if the OBD2 port was connected???

 

Ok...I got a little progress here.

First off, driving it in 3rd gives the same problem when kicking down into passing gear.

Second...I pressed and held the trip meter and turned on the ignition. This ran the system through a self diagnostic and cleared the check engine light. I then hooked up my ODBII scanner and voilah!! I got communication.

The codes it gave me were as follows.

P0121 TPS Voltage Does Not Agree With MAP
P1698 No mess received from TCM
P1694 No mess received from ECM

So now I am thinking the transmission control module may be the culprit. Anybody have any idea on how to test that??

 

Any updates on this?

 

I've checked all wire connections for the TCM and that didn't help.

Tomorrow morning at 9am I have an appointment at a local transmission shop for a full service. Flush, fill, filter, adjustment etc...If that doesn't fix the problem, my next step will be to hit the dealer to get them to clear and flash the TCM and if that doesn't fix it, I guess it's time to get an electrical specialist to start looking for bad grounds in the wiring harness.

I'll keep this thread updated as progress is made.

If anybody else has any suggestions, I am all ears.